Activated alumina (Al2O3) is widely used as a desiccant, catalyst, and selective adsorbent for water and gas contaminants. Al2O3 is typically synthesized from gibbsite (Al(OH)3), or materials containing gibbsite, by slow or flash dihydroxylation at temperatures exceeding 400° C. The resulting Al2O3 is in the form of fine mesoporous particles with poor physical integrity, having limited effectiveness in water treatment processes. To facilitate use in fixed bed reactor configurations, Al2O3 is usually aggregated in beads. Nevertheless, problems related to adsorbent stability, attrition, surface area decrease, and porosity reduction remain. In addition, the high temperatures typically employed in calcination of aluminum to yield Al2O3 limit the feasibility of forming hybrid media including Al2O3 by such methods.